(a) Field of the Invention
The present invention relates to a lower control system regulating the flow rate of lifting jack oil, more particularly to a mechanism that slows down oil flow under high oil hydraulic pressure and therefore achieve a slow and safe descending of a lifting jack.
(b) Description of the Prior Art
The conventional mechanism of reverse oil flow of a lifting jack utilizes a reverse flow valve to control oil in an inner chamber flowing back to an outer chamber, so that the lifting arm of a lifting jack may descend, restoring its the initial state. However, the conventional oil-reversing device cannot control the flow rate of lifting jack oil. Therefore, oil reversing under loading has a higher flow rate due to the high pressure in the inner oil chamber. As a consequence, the descending of the lifting arm of a lifting jack is swift under loading, which may endanger operational safety.
Accordingly, the primary object of the present invention is to provide a lower control system regulating the flow rate of lifting jack oil, which is suitable to be installed between a reverse flow valve and an inner oil chamber of a lifting jack to uniformize the oil flow rate in various loading situations. Especially when the jack is loaded, the control system slows down oil reversing to prevent the lifting arm from descending too fast.
To achieve above object, the present invention comprises an outer valve body, a steel ball, a spring, and a throttle body. The throttle body has a tapered portion, formed at its front end, and at least one throttling slot way and one lateral slot way, formed respectively on the tapered portion and the circumferential wall thereof. When the jack is not loaded, a reverse flow valve can lift the steel ball so that oil swiftly flows by the throttle body through the lateral slot ways to complete the reverse flow. When the jack is loaded, oil gently flows by the throttle body through the throttling slot ways, leading to a reduction of oil flow rate and a slower descending of the jack.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.